1. Field of the Invention
The present invention relates to a pressure medium-operated dispenser and, in particular to a pneumatically operated dispenser for dispensing a mass from a storage and dispensing container and which includes a housing, a dispensing device supported in the housing for displacement in a longitudinal direction of the dispenser and having a pressure medium-operated plunger, and at least one push member connected with the plunger and extending therefrom in a dispensing direction with the dispenser having a compression chamber for containing pressure medium for displacing the plunger, the dispenser further including a metering device for presetting an amount of mass to-be-dispensed by the dispensing device and including adjustment means for setting the metered amount, a carrier member cooperating with the dispensing device, and a return element for displacing the carrier member from its end position to its initial position.
2. Description of the Prior Art
Dispensers of the type described above are used for dispensing a metered amount of a mass, e.g., from a cartridge or a tubular bag, and are driven with compressed air or a hydraulic fluid. The dispensable mass has one or several components stored in one or several cartridges. The dispenser has, as discussed above, a housing and dispensing and metering devices. The dispenser is provided, e.g., with a receptacle or cradle for receiving one or more cartridges from which with the dispenser, the mass is brought out, in particular, is squeezed out. In the front region of the dispenser, there is usually provided a mixing element that mixes the dispensed mass components to a ready to-be-used mass. With a predetermined use, e.g., with chemical dowels, the metered mass amount is defined per one dowel. The metering device should insure a precise and timely delivery of the mass, e.g., in a borehole. For adjusting, in particular, for precise adjusting of the metered amount, the metering device is provided with adjustment means.
U.S. Pat. No. 5,020,693 discloses a dispenser having a housing, a dispensing device provided with an elongate pressing-out member, a metering device for preselecting a metered amount of the mass to be dispensed with the dispensing device, and an actuating unit for operating the dispenser. The metering device includes a return device, adjustment means for adjusting the metered amount, and a carrier or support member that cooperates with the elongate pressing-out member and that is returned from its end position to its initial position with the return device. The pressing-out member is supported on the housing for a longitudinal displacement and has several push members for squeezing a mass from a cartridge. The metering device has at least one stop displaceable in the longitudinal direction of the pressing-out member and which is securable to the housing with a locking screw.
The drawback of the dispenser, which is disclosed in U.S. Pat. No. 5,020,693, consist in that the return device or element at least somewhat displaces the screwed-to stop, which can change the preset metered amount. In addition, the adjustment of the metered amount with the adjustment means is unwieldy and not sufficiently precise.
Accordingly, an object of the present invention is to provide a pressure medium-operated dispenser that can be economically produced and which would insure a precise and convenient adjustment of the metered amount.
Another object of the present invention is to provide a dispenser in which an undesired change of the metered amount, in particular, during the operation of the return element is prevented.